Ladder leveling device



April 20, 1965 o. STUDER LADDER LEVELING DEVICE Filed May 21, 1963 Z6 742m E I NVEN TOR.

BY Lev/5 0. 511.1022 01 0A; SETTLE &CRAIG flrraRNE k5 ust My invention, herein after described and accompanied by drawings which show the various parts is a full disclosure to illustrate as clearlyas possible the functioning of the device so that a patent on same may be granted to me by the United States Patent Ofiice.

The object of the device is to provide means whereby a ladder equipped with such a device may be set on any terrain, level or unlevel, and still maintain the ladder in the desired position to facilitate the use thereof.

The amount of differential that this device will accomplish is limited only by the length of the legs and racks within the legs. However, for practical use,a differential of approximately sixteen to eighteen inches should prove sufficient for everyday use, but this is not to be interpreted to mean that the invention is to be limited to sixteen or eighteen inches. The differential to be decided upon should be left open for the eventual manufacturers and should be shown in the Letters Patent as such.

The following descriptions and accompanying drawings, with parts numbered to further clarify the description is offered wherein, like numbers refer to like parts.

FIGURE 1 is a perspective view of one embodiment in my ladder leveling device with parts broken away for the purpose of clarity;

FIGURE 2 is a side elevational view of the lower portion of the ladder leveling device of FIGURE 1 with parts broken away for the purpose of clarity;

FIGURE 3 is an enlarged sectional view of the dog structure illustrated in FIGURE 2; and

FIGURE 4 is an enlarged end view of the lowermost dog structure illustrated in FIGURE 1.

Referring to the drawing, a ladder 10 is provided having a pair of spaced apart legs 5, a interconnected by a plurality of spaced apart rungs 12 in the usual manner. The legs 5, 5a are channel-shaped and'are positioned with the channel opening facing outwardly.

A leg extension 14, 16 is slidably received in the lower end of each ladder leg 5, 5a. As will be noted in FIG- URE 2, the leg extensions have a generally rectangular cross section and are provided with a re-entrant opening 18. The leg extensions are received on a flanged keeper element 20 provided on each leg, the keeper element 29 projecting through the re-entrant opening 18 to retain the leg extensions within the channel portions of the ladder legs 5, 5a.

A shaft 2 extends through the hollow lowermost rung 12 and is suitably journaled therein for rotation. The ends of the shaft 2 extend through the re-entrant opening 18 and terminate within the leg extensions 14, 16. A dog 3, 3a is mounted on each end of the shaft. The dogs 3, 3a have a generally channel-shaped configuration with each end thereof being formed into a pawl 22, 22a and 24, 2411.

As will be noted in FIGURE 4, one of the dogs 3 is secured to the shaft 2 as by welding at 26 to prevent rotation of this dog with respect to the shaft. As shown in FIGURE 3, the other dog 3a is resiliently mounted on the shaft 2 to permit some pivoting of the dog 3a. The shaft 2 extends freely through the dog 3a. A leaf spring 7 is positioned within the dog 3a. The spring '7 is secured to the shaft 2 by means of a screw 28. The dog 3a is biased by the spring 7 to normally be in parallel alignment with the dog 3. However, when a force is applied to the dog 3a tending to rotate the dog about the United States Patent 0 shaft 2, the spring 7 will be deformed permitting some movement of the dog 3a with respect to the shaft 2. This feature is important in operation of the invention.

A ratchet element 4, 4a is provided on the inner face of wall 30, 36a of each leg extension 14, 16. The ratchet elements comprise a strip of metal having a plurality of longitudinally spaced slots 32, 32a. A coil spring 8, 811 extends from each dog into engagement with the keeper structure 9. The springs 8, 8a bias the dogs in a clockwise direction as viewed in FIGURE 2 to engage the pawls 2 2, 22a with one of the slots 32, 3.2a of the ratchet elements 4, 4-0. As will be appreciated, engagement of the pawls 22, 22a with the ratchet elements positively locks the leg extensions against withdrawal from the legs 5, 5a. However, engagement of the pawls 22, 22a does not positively lock the leg extensions against movement into the legs 5, 5a. If one of the leg extensions has been moved out of its ladder leg, such as the leg extension 16 as illustrated in FIGURE 1, it may be moved back into the leg 5:: by applying a force to the outer end thereof. The pawl 22a only frictionally restrains such inward movement. When a force is applied, it will tend to pivot the dog 3a in a counterclockwise direction as viewed in FIGURE 2. The leaf spring 7 will be slightly deformed permitting movement of the pawl 22a out of its slot 32a and thus permit inward movement of the leg extension 16. The leg extension 16 may be moved entirely into the leg 5:; with successive engagement and disengagement of pawl 22a with the slots 32a.

A camming element 6, 6a is provided within each leg extension 14, 16 at the lower end thereof. The cam elements 6, 6a havecamming surfaces 34, 34a for engagement with the dogs 3, 3a.

As shown in FIGURE 1, when one of the leg extensions 14 is moved inwardly to its fullest extent the camming surface. 34 causes the dog 3 to pivot in a direction to disengage the pawl 22 and engage the pawl 24 with one of the slots 32. The other dog 3a, which is connected to the dog 3 by the shaft 2, is also caused to pivot in the same manner. Engagement of the pawls 24, 24a with the slots 32, 32a positively locks the leg extensions 14, 15 against inward sliding and frictionally locks the leg extensions against outward sliding. As will be appreciated, one of the leg extensions, such as the leg extension 16 shown in FIGURE 1, may be drawn outwardly to the position shown by successive engagement and disengagement of the pawl 24a with the slots 32a in the manner which has been previously described.

The leg extension 16 is withdrawn from the ladder leg 5a a distance to compensate for any irregularities present on the surface Where the ladder is to be used. It will be appreciated that the leg extension 14 may also be withdrawn in the same manner as the leg extension 16. However, only one leg extension may be withdrawn because it is necessary for at least one of the cam elements 6, 6a to be in engagement with respective dogs 3, 3a in order to permit withdrawal of one of the leg extensions.

The dogs 3, 3a may be moved to an intermediate position by the cams 6, 6a where none of the dog pawls engage the slots 32, 320:. When the dogs are in this position, either leg extension 14, 16 may be freely moved out of its respective legs 5, 5a without ratchetting of the pawls 24, 24a. This procedure is convenient for easy adjustment of the leg extensions. However, once the leg extensions have been adjusted to the desired point, it is necessary to cam the pawls 24, 24a into engagement with the slots 32, 32a in order to prevent inward sliding of the extended leg. The weight of a person standing on the ladder assures engagement of the pawls 24, 24a.

aliases Having thus described my invention, I claim:

What I claim and desire to secure by Letters Patent is:

1. In a ladder comprising a pair of legs interconnected by a plurality of spaced apart rungs, a leg extension slidably mounted on the lower end of each ladder leg, locking means on each ladder leg normally engaged with the leg extensions to positively lock the extensions against outward sliding, lock actuating means on each leg extension adjacent the lower end thereof, each of said lock actuating means engageable with the locking means to actuate said locking means to positively lock the leg extensions against inward sliding and to frictionally restrain the leg extensions against outward sliding whereby one of said leg extensions is slidable outwardly for adjustment thereof with the lock actuating means of the other leg extension in engagement with the locking means.

2. In a ladder comprising a pair of legs interconnected by a plurality of spaced apart rungs, a leg extension slidably mounted on the lower end of each ladder leg, ratchet means provided on each leg extension, a shaft extending between the ladder legs, a dog including first and second pawls mounted on each end of the shaft for engaging the respective ratchet means, one of said dogs being fixedly mounted on the shaft and the other dog being resiliently mounted on the shaft, spring means biasing the first pawl of said dogs into locking engagement with the ratchet means to positively lock the leg extensions against outward sliding, a lock actuating element adjacent the lower end of each leg extension for engagement With the respective dogs upon inward sliding of either leg extension to move both first pawls out of engagement with the ratchet means and move both second pawls into engagement with the ratchet means, engagement of said second pawls positively locking the leg extensions against inward sliding and frictionally locking the leg extensions against outward sliding, one of said leg extensions being slidable outwardly for adjustment thereof with the lock actuating element of the other leg extension engaging its respective dogs.

3. In a ladder comprising a pair of legs interconnected by a plurality of spaced apart rungs, a leg extension slidably mounted on the lower end of each ladder leg, ratchet means provided on each leg extension, a shaft extending between the ladder legs and journaled therein, an arcuate dog on each end of the shaft, each of said dogs having a first pawl for engagement with the ratchet means for positive locking of the respective leg extension against outward sliding and frictionally restraining the leg extensions against inward sliding and a second pawl engageable with the ratchet means to positively lock the leg extensions against inward sliding and frictionally restrain the leg extensions against outward sliding, said dogs being pivotal a small degree with respect to each other whereby either of the leg extensions may be moved against the frictional restraint of its respective pawl while the respective pawl of the other leg extensions remains in engagement with the ratchet means, spring means biasing the first pawls of both dogs into locking engagement with the ratchet means to prevent outward sliding of the leg extensions, a lock actuating element adjacent the lower ends of each leg extension for engagement with the respective dogs upon inward sliding of either leg extension to pivot the dogs to move both first pawls out of engagement with the ratchet means and move both second pawls into engagement with the second ratchet means, one of said leg extensions being slidable outwardly for adjustment thereof with the lock actuating element of the other leg extension engaging its respective dog.

4. A ladder comprising a pair of ladder legs interconnected by a plurality of spaced apart rungs, said ladder legs each including a channel portion on the outer side thereof, a leg extension slidably received within the channel portion on the lower end of each ladder leg, keeper structure on each ladder leg engaged with the leg extensions to retain the leg extensions within the channel portions, ratchet means provided on each leg extension, a shaft extending between the ladder legs, a dog including first and second pawls mounted on each end of the shaft for engaging the respective ratchet means, said dogs being pivotal with respect to each other, first spring means on the shaft biasing the dogs into normally aligned relationship, second spring means biasing the first pawls of the dogs into locking engagement with the ratchet means to prevent outward sliding of the leg extensions, a camming element at the lower end of each leg extension for engagement with the respective dog upon inward sliding of either leg extension to pivot both first pawls out of engagement with the ratchet means and move both second pawls into engagement with the ratchet means, engagement of said second pawls positively locking the leg extensions against inward sliding and frictionally locking the leg extensions against outward sliding, one of said leg extensions being slidable outwardly for adjustment thereof with the camming element of the other leg extension engaging its respective dog.

5. In a ladder comprising a pair of legs interconnected by a plurality of spaced apart rungs, a leg extension slidably mounted on the lower end of each ladder leg, ratchet means provided on each leg extension, said ratchet means each having a plurality of longitudinally spaced slots, a shaft extending between the ladder legs, a dog including first and second pawls mounted on each end of the shaft for engagement with the respective ratchet means, said dogs being pivotal with respect to each other, first spring means on the shaft biasing the dogs into normally aligned relationship, second spring means biasing the first pawls of the dogs into slots in the ratchet means to normally engage the ratchet means to positively lock the extensions against outward sliding and frictionally restrain the legs against inward sliding, a camming element at the lower end of each leg extension for engagement with the respective dog upon inward sliding of either leg extension to pivot both first pawls out of engagement with the ratchet means and move both second pawls into slots in the ratchet means, engagement of said second pawls positively locking the leg extensions against inward sliding and frictionally restraining the leg extensions against outward sliding, one of said leg extensions being slidable outwardly for adjustment thereof with the camming element of the other leg extension engaging its respective dog.

References Cited in the file of this patent UNITED STATES PATENTS 644,567 Baetz Mar. 6, 1900 1,609,257 Lazear Nov. 30, 1926 2,113,282 Quinn Apr. 5, 1938 

1. IN A LADDER COMPRISING A PAIR OF LEGS INTERCONNECTED BY A PLURALITY OF SPACED APART RUNGS, A LEG EXTENSION SLIDABLY MOUNTED ON THE LOWER END OF EACH LADDER LEG, LOCKING MEANS ON EACH LADDER LEG NORMALLY ENGAGED WITH THE LEG EXTENSIONS TO POSITIVELY LOCK THE EXTENSIONS AGAINST OUTWARD SLIDING, LOCK ACTUATING MEANS ON EACH LEG EXTENSION ADJACENT THE LOWER END THEREOF, EACH OF SAID LOCK ACTUATING MEANS ENGAGEABLE WITH THE LOCKING MEANS TO ACTUATE SAID LOCKING MEANS TO POSITIVELY LOCK THE LEG EXTENSIONS AGAINST INWARD SLIDING AND TO FRICTIONALLY RESTRAIN THE LEG EXTENSIONS AGAINST OUTWARD SLIDING WHEREBY ONE OF SAID LEG EXTENSIONS IS SLIDABLE OUTWARDLY FOR ADJUSTMENT THEREOF WITH THE LOCK ACTUATING MEANS OF THE OTHER LEG EXTENSION IN ENGAGEMENT WITH THE LOCKING MEANS. 